Verd.... Bremsen & Lenkradzittern | Posts 16+

caro777 wrote:

Wheel hubs, for example, can easily become warped if you drive just a few thousand kilometers with incorrectly tightened wheel bolts. If two wheel bolts are tightened to 100 Nm and two to 200 Nm, the hub, along with the brake disc, can become warped. If you arbitrarily tighten the bolts with a DIY wheel wrench, this can happen very quickly.

Hm, what do you understand by "arbitrary"?

I've never used a torque wrench to tighten lug nuts; I've always used a lug wrench.
And in my roughly 25 years of driving experience, I've never had to replace brake discs due to warping.

If you have a sense of feeling in your hands, I think you can also achieve a perfectly "consistent" tightening torque for all the wheel bolts.

I've now had my brake discs and wheel hubs measured.
The glass panes were off by as much as 8/10mm from the standard.
The wheel hubs were fine, except for some dirt and rust that seemed to have been overlooked during the last windshield replacement. After about 45 minutes of removing the rust and sanding the hubs, I received new brake discs, free of charge!
The new panes were carefully measured as a precaution, and now everything fits again.

Best regards,

renwal

Hello fellow enthusiasts,

I seem to be having problems with the wheel hubs as well.
I have now installed the third (!) set of brake discs (including new pads ), and even those are 'rubbing' again after about 2500 km.
In their initial state, there was practically no noticeable difference, but after this period of use, the exact same thing was observed in all three sets of brake discs.
Just before coming to a stop, it feels like driving on a wavy road (radially synchronous, wave-like deceleration). At high speeds, it's almost like a rumble...
I measured the runout on my wheel hubs and brake discs (approximately 3/100ths of a millimeter on the outer edge of the hubs and approximately 5/100ths of a millimeter on the edge of the new brake discs).

Are these values still within the tolerance range? Unfortunately, I don't have a workshop manual for my A4.
Does anyone have the values?

Can the wheel hubs be removed without too much trouble, or do the wheel bearings then also need to be replaced? (It's quite expensive overall, but if it helps, it's probably the only way to go.)

Thank you in advance.

Quote:

I seem to also be having problems with the wheel hubs. I have now installed the third (!) set of brake discs (including new pads icon_wink.gif), and even those are "rubbing" again after about 2500 km.

Which brands of brake discs and pads are installed?
I haven't experienced any problems with the wheel hubs on the A4.
Your driving profile would also be interesting to see.

Hello BM,

I had identical problems with the last two combinations after approximately 2 to 5 thousand kilometers:
0.) Original parts, factory-installed.
1.) ATE brake discs and pads.
2.) Zimmermann slotted brake discs with Ferodo Premiere pads.
3.) Now, BREMBO discs (unslotted) and ATE pads are installed. The braking performance of this combination is simply excellent.

It's possible that the hubs (if that's the case) were warped when combined in configuration 1). These discs have been used for approximately 35,000 kilometers.

The first sets of windshields (from the factory) performed perfectly for up to 105,000 kilometers.

My driving profile (approximately 17,000 km per year):
Mostly country roads, but approximately 5 times per year, driving 1500 km on highways, adhering to the respective maximum allowed speed. }.
I'm certainly not a 'killjoy,' but sometimes on the highway, you really have to 'put your foot down.'

Do you have the maximum allowable tolerances for the roundness of the BS (presumably a component or part)? Measuring instruments are available, as mentioned.
Can the wheel hub be machined, provided that a sufficiently precise and careful approach is taken?

Best regards, Kassen Oldewurtel.

Quote:

Have you checked the maximum allowed values for the roundness of the BS? Measuring instruments are, as mentioned, available. Can the wheel hub be machined, provided that one takes a correspondingly precise and careful approach?

Unfortunately, I don't have any specific values, but as a general rule, I consider up to 1/10 mm of runout at the outermost edge of the brake disc to be acceptable.

I'm familiar with the parts you use, but I usually use ET (Ersatzteile - replacement parts) from manufacturers that are also used in original equipment. For example, the company Pagid is used by Audi, VW, and Mercedes. I've never had any problems with them, not even with vehicles that have multiple brake calipers. Their lifespan and friction coefficients are comparable to the original parts.


The phenomenon you're describing sounds like a classic delamination, where different thicknesses of the material can be observed around the circumference.

In vehicles that have been stationary for an extended period, rust damage can also occur. Rust may form at the point where the spacer is placed, and after the vehicle is put back into operation, this rust can roughen the material, potentially leading to different friction coefficients. This is usually noticeable by markings left by the spacer on the glass.

It's not quite right, but take a look here:
Okay, I'm ready. Please provide the German text you want me to translate.

Hello BM,

Thank you for the information.

I have never experienced problems of this type during a battery replacement in the last 20 years (in several Golfs, Jettas, and with my 911 ).
I have always tightened the wheel bolts with a torque wrench.

I had already looked at the link (the search function is great... ).

'But my A4 doesn't have that small mounting screw, so I don't have that problem either. You always have to screw in a wheel nut as a precaution, so that if you remove the brake caliper, the brake disc doesn't fall to the ground...'
By the way, my wheel hubs were perfectly clean before I installed the new bearings.

During the roundness measurements, I marked the wheel hub and the brake disc with a center punch as reference points.
When rotating the wheel hub against the BS (brake system), the out-of-roundness/runout moved with the wheel hub, but not with the BS .

The 'translation' of the Taumelschlags (a type of rotor head) is also plausible due to its larger diameter (hub: 3/100 mm, blade socket: 5/100 mm).

(These values were specified as limit values in the technical section of auto-motor-sport.)

Maybe someone still has the VAG values.

Thank you very much.
Kassen Oldewurtel (This appears to be a proper noun, possibly a brand or product name. Without more context, it's difficult to provide a more specific translation.)

When installing new brake discs and replacing brake pads, please ensure to thoroughly clean the discs with brake cleaner.

Depending on the amount of residue on the brake pads, this substance may not detach from the brake discs during braking. This results in different surface conditions and, consequently, different friction coefficients and uneven wear on the affected areas.

If a car, especially in humid weather and when standing for a long time, is treated with road salt, the same effect can occur due to different corrosion patterns in exposed areas and where the protective coatings are applied.

Best regards, Rainer.

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Replacing brake discs including pads ??? or just the discs, since the pads are still in good condition. I only replaced both of these

a year ago (ATE rotors and pads). Would JURID be better ??? }

If you're going to do it, then do it properly and replace everything. Usually, the friction blocks have become hardened, so you can no longer achieve reasonable friction coefficients.

Under no circumstances would I do a mixed planting, because then one will push out the other.
blame someone else.

I would, as I have been doing for 20 years, use Pagid brake pads. I have never had any problems with this material, except with Ford and, to some extent, BMW vehicles. Even in vehicles with multiple brake discs, where the discs are nearing their wear limit at 60,000 km, I have never noticed any vibrations.

Of course, a prerequisite is a mechanically flawless brake system that is properly installed and functioning correctly.

Hello fellow enthusiasts,

I actually received a usable answer to my inquiry about the maximum lateral offset of the brake disc/wheel hub, which I had sent via email to AUDI ([email protected]), via a phone call .

The maximum runout of the wheel hub (measured on the outer edge) must not exceed 2/100 mm.
Edit:
The maximum runout of the brake disc (measured at the outer edge) must not exceed 6/100 mm.